I feel for you. We have the same thing. Several times a year, I go in there with an air hose, blowing out the crap that accumulates. If not, it would rot, retain moisture and attract unwanted visitors. I don't know of a solution that does not involve major reconstruction of the deck.
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user558Jun 16 '12 at 20:29

How is this even to code? I just don't comprehend how such things can even be allowed in this day and age. I suppose if you could pull the deck back at least a couple feet without unseating the posts then it is possible, but honestly if they were too cheap to build the deck off of a properly secured ledger board then I would worry about what else they cheaped out on. If it were me I would do a total rebuild.
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maple_shaftJun 18 '12 at 11:30

3 Answers
3

Cut back the siding above the ledger in two places - right at the top of the ledger and 1" above the level of the board that goes over the ledger. Loosen the siding left above the ledger so that you can slip flashing under the paper under the siding. Run flashing behind the siding and over the ledger as should have been done in the first place. This should work if the ledger and the siding under it is still in reasonably good shape and you have a good strong ledger connection to the house with lag bolts.

Be careful that you don't destroy the tar paper under the siding. Cut the siding just short of that depth and then have fun trying to pry the siding out.

Do your plan except cut the joist about 3' from the side of the house.

Install the ledger an then sister the removed joist section back into placed with 6' sections of 2x8 or 2x6 (whatever the joists are) with several nuts and bolts.

If the support posts really get in the way of this, then make the splice between the first and second posts instead of the first posts and the wall.

Unless the deck is terribly difficult to take apart (rusted/stripped screws), this project should only take about two days (50% of which would be installing the ledger and flashing) if you have an impact driver (or even a decent drill/driver) and a good set of bits (Milwaukee Shockwave bits... Dewalt Impact Ready bits are terrible [they break and have other huge problems too].)

Things to keep in mind:

Don't get the deck boards all mixed up, and they'll all fit back
together nicely.

Try to make a nice, clean cut on the joists, don't get them mixed up
either. Any additional cuts to adjust their length should be made on
the side that joins up with the ledger. (This will ensure that the
joists fit back together nicely at the splice.)

As an alternative could you convert this to a freestanding deck? Add post and piers near the house. Install some blocking to replace the crummy ledger you'll soon remove. Pull up your one row of floor boards and chop the deck shy of the wall.